Known cable connectors include a plug or coupler which is provided with a sleeve extending over the cable end to be connected and surrounding a strain relief ring, a contoured annular seal and a thrust collar which axially compresses the seal upon insertion of a screw plug so that the seal radially bears inwardly against the cable insulation and radially bears outwardly against the inside of the sleeve.
For attaining a sealed or tight connection between the sleeve and the cable end or also for sealing a cable bushing, the so-called "packing box principle" is frequently applied in which a hollow screw turned into the sleeve axially compresses a rubber ring against a metallic collar or the like so as to be expanded radially inwardly and outwardly for providing the desired sealing action.
This principle may seem to be sound, however, it frequently happened that the radial pressure exerted on the cable or its outer insulation exceeded admissible limits thereby resulting in a constriction because of the cold flow of the outer and/or inner cable insulation. Thus, the strength and in particular the electric properties of the cable are impaired e.g. a local decrease of the wave impedance in coaxial cables.
It was thus proposed to modify the strain relief ring, which also provides the contacting of the outer conductor of the cable with the metallic sleeve, with a ring-shaped cutting edge directed toward a shim-type thrust collar while the contoured annular seal includes a V-shaped cross section open toward the cutting edge. Thus, the screw plug can be tightened only until the cutting edge bears against the thrust collar whereby the annular seal is severed.
Since the displacement and thus the compression of the seal is at most equal to its width in axial direction as measured at the tip of its V-shaped notch, a reliable sealing is attained only when maintaining narrow tolerances especially of the outer conductor of the cable. However, since cable connector and cable are delivered by different producers, the admissable tolerances are frequently exceeded. Furthermore, a careful assembling is required. In particular, the contoured ring must be placed over the cable with correct orientation in order to provide the V-shaped notch in direction toward the strain relief ring. A further drawback resides in the fact that the strain relief ring, annular seal and thrust collar are furnished as loose parts and thus must be handled separately during assembling.